First published online February 12, 2004
Journal of Cell Science 117, 603e (2004)
© The Company of Biologists Limited
A life-saving prion?
Misfolding of proteins causes several diseases, including cystic fibrosis and emphysema. Moreover, in prion diseases, such as BSE and CJD, this misfolding is infectious and thought to be transmitted by rogue proteins (prions) that impose their structure on the normal native protein. Chaperone proteins play a critical role ensuring that proteins do not misfold. The chaperone calnexin, for example, is essential for yeast survival. Luis Rokeach and co-workers now suggest that, bizarrely, a prion might allow cells to survive the otherwise disastrous consequences of protein misfolding in the absence of chaperones (see p. 907). They have isolated a yeast strain that can survive without calnexin. The genetic element responsible (Cif) displays non-Mendelian inheritance and can be transferred in cell extracts. Moreover, it is sensitive to protease treatment but not nucleases – all of which implicates a prion. Cif only seems to appear spontaneously in cells that contain a mutant form of calnexin that lacks the conserved central region. This non-functional calnexin chaperone might therefore titrate out a cellular factor that usually inhibits the structural change that converts Cif's normal cellular counterpart into an infectious prion.
Related articles in JCS:
- A non-chromosomal factor allows viability of Schizosaccharomyces pombe lacking the essential chaperone calnexin
- Philippe Collin, Pascale B. Beauregard, Aram Elagöz, and Luis A. Rokeach
JCS 2004 117: 907-918.
[Abstract]
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